Majunga, an “exceptional” HQE tower

Emblematic of the revival of La Défense, the Majunga tower stands out through its strong architectural ambition and its environmental performance.


Tour MajungaBuilding began on the Majunga tower in July 2014 in the heart of the business district of Paris-La Défense. This high-rise building, with its remarkable environmental excellence, had already obtained the BBC (Low Consumption Building) label during its design phase, as well as HQE (High Environmental Quality) and BREEAM (BRE Environmental Assessment method) certification, both at “Excellent”.

Winner of the BREEAM Awards 2012, it achieved a score of 77.43% at the late design phase, “the highest level of environmental performance in Continental Europe, out of all assets in 2011” explains the developer Unibail-Rodamco.  The energy efficiency targets of the tower (44 floors, 69,500 sqm net floor area) primarily rely on:

  • a high-performance building envelope that stands out through its façade;
  • natural ventilation openings adapted to the constraints of a high-rise building and controlled by BMS (centralised building management)
  • a 250 sqm photovoltaic system;
  • optimisation of the amount of natural light and control of artificial lighting
  • recovery of rainwater for the gardens on the terrace

Its outstanding environmental performance will enable users to significantly reduce their energy consumption and their carbon footprint. “Majunga is a strong and balanced project across all areas of environmental performance, and is not only efficient in terms of energy matters but also in the management of water, materials, waste and movement, while respecting the original intentions of the architectural agency Viguier” insists Thierry Deberle, manager of Elioth Energie & Environnement at Egis.

Majunga is also the first tower in La Défense with outdoor spaces on each floor (loggia or balcony)

Egis carried out the structural studies for the tower, overall calculations of operational details through testing soil-structure interaction, dynamic behaviour and prediction of subsidence.

For this project, Egis teams also contributed their skills and expertise to environmental engineering tasks, advanced HQE-BREEAM studies, optimisation of daylight through simulation, energy consumption and comfort through dynamic thermal simulation, optimisation of natural ventilation through ventilation simulation, waste and water management, monitoring of the green construction and the HQE and BREEAM certification process.


Carb’Elioth, the carbon calculator to assess the GHG emissions related to construction, operation and the demolition of buildings to help with design

The tool takes into account the carbon emissions of materials and their transportation as well as the building’s energy consumption throughout its life.

The objective of Carb’Elioth is to enable project managers to establish a simplified carbon footprint of their project in just a few minutes, even if they are not experts in this field. Indeed, one of the challenges is to be able to inform partners, architects and project owners about the emissions generated by projects well in advance, and advise as to the most virtuous possible solutions.

This tool also helps give baselines for evaluating projects, which helps to establish their “carbon performance”.  For example, a “classic” concrete office building emits on average 120 kg CO2e/m² during its construction. According to a series of studies carried out, it was found that the structure represents about 60-70% of the materials emissions. The façade accounts for about 10% while the finishings represent around 20%, much of which is due to flooring. The designer’s total leverage (by playing around with the choice of materials) is around 50%. An all-wood building that uses all the “best carbon options” for the façade and finishings would therefore be around the 60 kg CO2e/m² mark.





Energy management for buildings : a focus on major savings

As the exclusive tenant of the Terra Nova 3 building in Montreuil, Egis has embarked on a continuous process to optimise its energy and environmental performance. In just one year, Egis achieved 16% savings

Egis implemented the Ubigreen Performance energy management solution to continuously monitor the energy consumption of a first pilot site, located in Montreuil – the Terra Nova III building. The daily monitoring of usage helped to quickly detect problems such as overconsumption of energy, and provides the operator with immediate corrective actions. A weekly report was published by the Energy Manager in charge of the building, allowing a quicker response for the implementation of action plans, in a bid to continuously improve the site’s energy performance.

Terra Nova à MontreuilIdentity of the Terra Nova 3 building:

Built in 2005

6 floors and 2 basement levels

1600 sqm net floor area per floor

10,000 sqm net floor area

An all-electric building

A company canteen

Anne-Marie Ferron-Menard, head of “existing buildings” activities at Egis, explains: “The daily monitoring of energy consumption using 54 sensors is used to quickly detect anomalies and provide the operator with immediate corrective actions. A weekly report is published, contributing to the continuous improvement of the site’s energy performance”.


Instrumentation + tracking software and smart thinking = considerable savings 



In 2016, the initiative was launched at the START building (headquarters of the Egis group in Guyancourt, France) – stay tuned!



Egis awarded a golden CUBE at the CUBE 2020 contest for 2015-2016 

Terra Nova 3 finished in 8th place overall in 2016 and 1st in the certified buildings category. The Start site at Guyancourt was not going to be outdone, finishing 3rd in the buildings of more than 12,000 sqm category with an energy saving of 19% compared to the previous year.

Germain Poirot, Head of Energy Management at the Egis group believes that “Egis has deployed its energy management solution, based on the technical expertise and involvement of all stakeholders, for the benefit of the energy performance of buildings. This system was successful thanks to the involvement of a range of stakeholders; the energy manager, the operating team and general resources who have worked together to find solutions to the various challenges of implementing energy-saving actions. Awareness campaigns among users were organised to get employees on board so that everyone adopts eco-responsible behaviour in their workplace. Our energy management strategy is demonstrating its long-term effectiveness. The continued reduction over two consecutive years within Terra Nova 3 shows that our strategy is working long term. We are very proud of the commitment and motivation of the teams. We plan to continue this optimisation work, and roll out this initiative across all Egis sites.

This initiative was awarded the silver cube at the CUBE Contest 2020 for the year 2014-2015 : The awards ceremony for the CUBE Contest 2020 (Concours Usages Bâtiment Efficace) was held on Wednesday 18 March at the headquarters of BNP Paribas Real Estate in Issy-les-Moulineaux. For decreasing its energy consumption by 16% at the Terra Nova III building, which houses its Montreuil teams, Egis was awarded the silver cube in the category of certified office buildings of over 10,000sqm.


  • 385 MWh of savings
  • 16% energy savings
  • 50,000 euros in financial savings



Watt bridge, an energy positive walkway

A footbridge in Venlo, the Netherlands

elioth-inventors-designers-engineers-google-chrome_2016-07-19_11-50-32As part of a call for tenders, Egis proposed a footbridge design in complete harmony with its setting. To protect passers-by from prevailing winds, nine wind turbines would be installed on the downstream side to slow the flow of air. They should allow a nominal power output of around ten kilowatts, enough to power the lighting near the site or to light the local neighbourhood.

Geothermal power in metro station facilities

Powering 127 homes and two office areas

The rise in the consumption and cost of energy sources, and the desire to reduce greenhouse gas emissions, mean that geothermal energy is now more attractive than ever. By capitalising on its synergies and partnerships, Egis was keen to improve the technical framework (currently still at the experimental stage) in the field of geothermal piles. An exciting challenge launched during the creation of a second metro line in Rennes and a first in France.

Métro Rennes géothemie 2 © Egis

In December 2010, Rennes Métropole entrusted Egis with the EPCM (infrastructure and buildings) for line B of the Rennes metro, with one key challenge: the integration of geothermal energy in four stations. Not to heat or cool the stations, as had already been done in Austria, but to supply power to the 127 homes and two office areas that will be built over this transport line in coming years. Using walls in direct contact with the ground, the geothermal system will recover heat during the winter and cold air in summer. Heat pumps will collect low-temperature energy from the ground and bring it to a temperature sufficient for heating buildings, i.e. temperatures between 30°C and 75°C. The stations’ concrete walls are used as thermal storage.

Adapting a very low energy technique for geothermal capture to a complex civil engineering work

The innovation focused on analysing the behaviour of a structure under unusual thermal loads, and the incorporation of a geothermal system into a civil engineering structure.
Delivery is scheduled for 2019/2020.
In terms of sustainable development, in addition to the geothermal aspect, other features make this an exemplary project:

  • a maintenance workshop heated with wood and powered by photovoltaic panels
  • the choice of a low carbon footprint cement
  • lighting with presence detection for the site facilities…

These are all examples of the project owner’s desire to control energy costs at all stages.


An eco-comparator of road variants for climate change mitigation

Variways®, the Egis eco-comparator for road project variants, is designed to assess the carbon impact of road infrastructure during construction and operating phases, by means of two indicators: greenhouse gas emissions and energy consumption. Egis offers associated services to project owners who are concerned about the environmental impacts not only of their new projects, but also their expansion and development projects, in France and abroad.


Road infrastructure, a major consumer of fossil energy resources, is the source of nearly 70% of greenhouse gas (GHG) emissions from the transport sector. In this era of energy transition, controlling GHG emissions is crucial right from the design phase, and key to providing sustainable development solutions.

Contexts and Challenges

Commitment to environmental performance requires the evaluation and control of GHG emissions and energy consumption. On the basis of current knowledge, the construction (materials manufacturing and transport) and operating (vehicle emissions) phases of road projects are known to produce 10% and 90 % of GHG emissions respectively. Keenly aware of the challenges involved, Egis has developed Variways®, a tool for evaluating a road project’s carbon impact during the construction and operating phases.


Variways® is a decision-making software that helps clients to choose the most suitable road or motorway variant. Its aim is to offer users optimised “carbon design” in terms of GHG emissions and energy consumption. From the design phase, the software provides Clients with quantitative indicators allowing them to optimise their projects and to make their choices regarding variants. The indicators take account of the initial investments related to the construction phase and of the effects induced by the operating phase. In this way, Variways® allows project owners to contribute to one of the shared goals of the European Union and the French Grenelle Environment Forum: a 20% reduction in GHG emissions by 2020 (in comparison to 1990 levels).


Variways® has interactive menus that make it easy to integrate project geometry, as well as all of the parameters needed to calculate indicators for the operating and/or construction phases. Three main sets of input data are needed to calculate the indicators for the operating phase: route geometry, anticipated traffic and vehicle speeds. For the construction phase, Variways® uses twenty geometric and environmental parameters to assess the GHG emissions resulting from earthworks and from the construction of pavements, drainage, structures, tunnels and road furniture. These elements are then coupled with information stored in the program’s data base (vehicle types, construction equipment, etc.) to calculate GHG emissions and energy consumption during a given construction phase and operating period. Variways® is also able to give results in monetary terms by assessing the estimated annual cost of a ton of carbon. The software also provides the possibility of printing out different types of output data (tables, histograms, maps) in easily understood and clearly presented formats. Variways® is the first eco-comparator for road variants to have been used on projects both in France and abroad. The “operation” section of Variways® has been certified by France’s institute for roads, streets and transport infrastructure (IDDRIM).

Link to the IDRRIM technical opinion

Construction Module Operating Module

Pour en savoir plus


Stabilised and reinforced soil using vetiver

A plant with deep roots (3-4 m) that helps to combat soil erosion and stabilise road embankment.

This solution received the Caisse des Dépôts 2013 Innovation and Sustainable Development award. Used successfully in Brazzaville (Congo), it has helped to avoid the use of heavier and more expensive construction materials that would have had an impact on the landscape, as well as contributing to improving the living conditions of inhabitants.

Closely planted, vetiver grows in dense hedges that reduce water speed on the soil surface, and encourage infiltration. Its deep roots (3-4 m) give it good anchorage even in unstable soils. Vetiver can therefore withstand winds and sandstorms. This morphology means that slopes can be stabilised by stopping or slowing down erosion.
Soil erosion, exacerbated by climate change, is a threat to infrastructure of all kinds, including homes and consequently the population. The use of vetiver, a locally grown plant, avoids the use of heavier and more expensive construction materials that would have had an impact on the landscape, as well as contributing to improving the living conditions of local people.

Benefits: including vetiver in more conventional anti-erosion solutions (gabion walls, concrete, drainage, earthworks, etc.) allows us to:

  • optimise implementation and reduce costs (more than 13 times cheaper than solutions such as gabion or concrete walls); vetiver requires very little water (irrigation)
  • maintain local homes
  • develop local employment (an initiative that requires intensive local labour. It provides jobs in nurseries, on work sites and in maintenance)
  • improve the living environment through a green canopy.
  • enrich the soil (increases fertility)
  • absorb and sequester carbon from the atmosphere
  • fight against insects and other pests (e.g. termites)
  • build a habitat for flora and fauna
  • use local resources (vetiver is grown for its essential oil)


vetiver 1(c) Alain NDNONA vetiver 2 (c) Alain NDNONA vetiver 4 (c) Alain NDNONA vetiver 5 (c) Alain NDNONA

For more information, see the leaflet ” Vetiver grass: an innovative technique for soil stabilisation”

The NEF, a social rehabilitation project with exceptional architectural and energy performance

The Nef project, in Tours, has received the Silver Pyramid award. It was recognised by the French Federation of Property Developers (FPI) for its aesthetic and environmental performance.

NEF © Boille & Associés Architectes (1)

  • The entire property, built on the site of a former postal sorting office on Rue Blaise-Pascal, was designed to generate just as much energy as it consumes.
  • The use of geothermal power, the addition of 1500 sqm of photovoltaic panels, and the sharing of technical facilities by residents and staff (only three lifts have been installed) allow the Nef to generate as much, if not more, energy than it consumes.
  • An innovative geothermal system: it heats the housing, while the cold air is stored to cool offices, via radiant ceilings. This principle helps achieve a satisfactory level of comfort without air conditioning.
  • The roof terrace is equipped with 1600 sqm of photovoltaic panels to produce approximately 240,000 kWh/year.
  • The building’s energy performance is monitored using an internet portal allowing each inhabitant to monitor their own energy consumption in real time. The instructions for the building are provided for future residents.
  • Rainwater from the rooftops is recovered for domestic use (supplying toilets and watering the vegetated façade that will cool down the building naturally during the summer).
  • All insulation components and the framework of the homes on the terraces are made of wood, which significantly reduces CO2 emissions.
Link to the Spotlight on SD

Energy transition, the key to renovating university assets in Rennes (French town)

With their 55,000 students and staff, and a property portfolio of 450,000 sqm spread over eight main campuses (in Rennes and across Brittany), the University of Rennes 1 and 2 are setting their sights firmly on the challenge of Energy Transition:  while the ever-increasing pressure of water and energy on university budgets requires the activation of any and all sources of savings, universities have on the whole decided to focus on creating value and establishing a long-term vision.

Schéma directeur énergie eau (SDEE)

For this project, Egis, together with its partners Graines de Changement (Seeds of Change, supporting mobilisation), FCL (for the financial aspects) and Earth Avocats (for legal and contractual expertise) was commissioned by the universities to complete a Water and Energy Master Plan (WEMP). Based on a detailed analysis of the university’s assets, a multi-year investment plan and a transition roadmap were established.

The Caisse des Dépôts et Consignations, the City of Rennes, Rennes Métropole, the Brittany region, the ADEME and the French Water Agency are also fully on board, supporting the universities by financing and managing the WEMP.



The missions led by Egis

Analysis of what already exists

  • In situ diagnosis of buildings, water and energy networks
  • Mapping of exploitable renewable and intermittent resources
  • Creation of an organisational chart for managing Water and Energy
  • Benchmarking, and identification of regulatory constraints and financial opportunities.

In pursuit of potential savings

  • Ranking of measures for creating Water and Energy savings and search for
  • the most effective sets of actions across the site.
  • Development of a WEMP steering tool.

Definition of the WEMP

  • Finding financing mechanisms and appropriate legal arrangements
  • Development of the Master Plan and associated operational documents.

The WEMP was implemented from October 2013 until mid-2015. It turned out to be a valuable tool for the campuses’ sustainable development approach, in line with Agenda 21 on Rennes 1 and the sustainable development strategy of Rennes 2.

The implementation of the WEMP on campus allowed teams to experiment and innovate in matters of:

  • water & energy savings, with the involvement of students and researchers.
  • cooperation and joint development to unite all campus users around a common project for a high quality work environment, and a sustainable university.


Adapting road infrastructure to climate change

roadapt © iStock_Chatchai SomwatThe ROADAPT project is about prioritising adaptation measures in order to maximise service availability at a reasonable cost. It adopts a risk-based approach using the RIMAROCC framework (Risk Management for Roads in a Changing Climate), which was developed as part of ERA NET ROAD in 2011. The approach addresses the causes, effects and consequences of weather-related events to identify the main risks that require action through the implementation of mitigating measures.

The ROADAPT project is part of the CEDR “Transnational Road Research Programme on Climate Change” (funded by the national road authorities of the Netherlands, Denmark, Germany and Norway). The ROADAPT consortium consists of the following partners: Deltares (The Netherlands, coordinator), SGI (Sweden), Egis (France) and KNMI (The Netherlands).

Find out more

Roads for today, adapted for tomorrow Guidelines (may 2015) Deltares, coordinateur du projet